1. Field of the Invention
The present invention relates to polypropylene resin compositions and to injection molded articles made therefrom. In particular, the invention relates to a polypropylene resin composition which has superior fluidity and which is useful as a raw material of molded articles having good balance between rigidity and impact resistance and having, if any, unnoticeable weld lines and flow marks, and to a molded article made therefrom.
2. Description of the Related Art
Polypropylene resin compositions are materials excellent in rigidity, impact resistance, etc. and therefore are used for a wide variety of applications in the form, for example, of automotive interior or exterior components and housings of electric appliances.
For example, JP 9-71711 A discloses a propylene-based resin composition which includes a crystalline propylene-ethylene block copolymer including a propylene homopolymer portion and an ethylene-propylene random copolymer portion having an ethylene content of from 20 to 80% by weight, a melt flow rate (MFR) of from 25 to 140 g/10 min and an ethylene-α-olefin copolymer having a MFR of from 0.5 to 15 g/10 min, an ethylene triad sequence fraction of from 55 to 70%, and talc.
JP 2000-26697 A discloses a propylene-based resin composition which includes a crystalline propylene-ethylene block copolymer including a polypropylene homopolymer portion and an ethylene-propylene random copolymer portion having an ethylene content of 30% by weight or more and a weight average molecular weight of from 200,000 to 1,000,000; an ethylene-α-olefin or ethylene-α-olefin-diene copolymer rubber having an MFR of from 0.05 to 1.2 g/10 min; talc and a high density polyethylene having an MFR of 11 g/10 min or more.
JP 2000-178389 A discloses a polypropylene resin composition which includes a propylene-ethylene block copolymer including a propylene homopolymer portion wherein the MFR of the propylene homopolymer portion is 100 g/10 min or more and the MFR of the block copolymer is from 55 to 200 g/10 min; an ethylene-α-olefin copolymer rubber having an MFR of less than 0.9 g/10 min and a comonomer content of 28% by weight or more; and talc.
However, regarding molded articles made from the polypropylene resin compositions disclosed in the above-cited references, there are demands for improvement in balance between rigidity and impact resistance and elimination of weld lines and flow marks.